Solution-processed Tb: Zr co-doped In2O3 thin film transistor and its dual effect on improving photostability

In this paper, Tb: Zr co-doped In2O3 TFTs were fabricated using an aqueous route. The dual effect of Tb: Zr codoping on improving photostability was addressed. At a 5 mol% co-doping concentration, the Delta Vth under NBIS first decreased and then increased as Tb: Zr ratio increased. The optimized co-doped sample (1: 2) showed a Delta Vth of -3.22 V, compared to the undoped sample of -9.5 V and the single-doped samples (1: 0 and 0: 1) of -4.4 V and -4.15 V respectively. The defect state was evaluated using mu-PCD. The peak value and tau 2 first decreased and then increased with an increase in Zr ratio, and reached their minimum values when the Tb: Zr co-doping ratio was 2: 1 and 1: 2, respectively. This suggested that co-doping can introduce more deep level states for the rapid recombination of photogenerated carriers and reduce shallow level states, leading to superior photostability of the co-doped devices. Further characterization by UV-Vis and XPS indicated that the increase in band gap and the decrease in oxygen vacancy were also contributing factors to improved device stability. These results highlight the great potential of solution-processed Tb: Zr co-doped In2O3 TFT for applications in low-cost and high-stability electronics.